U.S. patent application number 11/722846 was filed with the patent office on 2008-02-21 for 3d image display method.
This patent application is currently assigned to JAPAN SCIENCE AND TECHNOLOGY AGENCY. Invention is credited to Tomohiro Endo, Naoki Kawakami, Susumu Tachi.
Application Number | 20080043014 11/722846 |
Document ID | / |
Family ID | 36614626 |
Filed Date | 2008-02-21 |
United States Patent
Application |
20080043014 |
Kind Code |
A1 |
Tachi; Susumu ; et
al. |
February 21, 2008 |
3D Image Display Method
Abstract
A stereoscopic image display method capable of stereoscopic
display of a photographed image. One two-dimensional image is
selected, and one pixel capable of being viewed from a
corresponding viewpoint position is selected from a plurality of
pixels. A virtual surface with the selected two-dimensional image
pasted thereon is assumed, and the virtual surface is arranged so
that an image center point of the two-dimensional image
corresponding to a center of an object coincides with a center of a
display surface. Next, a virtual extension that extends from the
viewpoint position to the virtual surface through the selected
pixel is assumed. A color on the two-dimensional image assumed to
have been pasted on the virtual surface, corresponding to a point
of intersection between the virtual extension and the virtual
surface is determined as a display color of the pixel positioned in
a direction extending from the pixel to the viewpoint position.
Inventors: |
Tachi; Susumu; (Tokyo,
JP) ; Endo; Tomohiro; (Nagoya-shi, JP) ;
Kawakami; Naoki; (Tokyo, JP) |
Correspondence
Address: |
RANKIN, HILL, PORTER & CLARK LLP
38210 Glenn Avenue
WILLOUGHBY
OH
44094-7808
US
|
Assignee: |
JAPAN SCIENCE AND TECHNOLOGY
AGENCY
4-1-8, Honcho
Kawaguchi-shi, Saitama
JP
332-0012
|
Family ID: |
36614626 |
Appl. No.: |
11/722846 |
Filed: |
June 27, 2005 |
PCT Filed: |
June 27, 2005 |
PCT NO: |
PCT/JP05/11738 |
371 Date: |
August 17, 2007 |
Current U.S.
Class: |
345/419 ;
348/E13.022; 348/E13.03; 348/E13.056 |
Current CPC
Class: |
G02B 30/27 20200101;
G03B 37/00 20130101; G03B 35/18 20130101; H04N 13/31 20180501; G02B
30/54 20200101; H04N 13/393 20180501; G03B 35/04 20130101; G06T
15/00 20130101; H04N 13/275 20180501 |
Class at
Publication: |
345/419 |
International
Class: |
G06T 15/00 20060101
G06T015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2004 |
JP |
2004-381985 |
Claims
1. A stereoscopic image display method that uses a
three-dimensional display apparatus to present a stereoscopic
image, which can be visually recognized by naked eyes, to a person
located outside the three-dimensional display apparatus having a
cylindrical display surface defined therein, the display surface
being formed of a plurality of pixels respectively configured to
emit light of different color and brightness as defined according
to an angle at which the pixel is viewed on a horizontal plane, the
method comprising: a first step of defining a center point of an
object to be displayed as the stereoscopic image, and photographing
the object by a photographic device in all directions from an
outside of the object, centering on the center point of the object
to thereby obtain a plurality of two-dimensional images, or
creating by computer graphics technology a plurality of
two-dimensional pseudo images comparable to the two-dimensional
images to be obtained by photographing the object from the all
directions from the outside of the object, centering on the center
point of the object, and using the two-dimensional pseudo images as
the two-dimensional images; a second step of selecting from among
the two-dimensional images one two-dimensional image and selecting
from among the pixels one pixel which can be viewed from a
viewpoint position corresponding to the one two-dimensional image
which has been selected; a third step of assuming a imaginary plane
onto which the one two-dimensional image selected is pasted, and
arranging the imaginary plane so that an image center point of the
one two-dimensional image corresponding to the center point of the
object may coincide with the center of a cylindrical space for the
cylindrical display surface and that an angle formed between the
imaginary plane and a straight line connecting the viewpoint
position and the center of the cylindrical space for the
cylindrical display surface matches an angle formed between an
image pickup surface of the photographic device and a straight line
connecting the center point of the object and a principal point of
the lens of the photographic device; a fourth step of assuming an
imaginary extended line which extends from the viewpoint position
to the imaginary plane through the one pixel selected; a fifth step
of determining a display color of the one pixel as viewed from the
viewpoint position, based on a color of a point on the
two-dimensional image assumed to have been pasted on the imaginary
plane, the point corresponding to a point of intersection of the
imaginary extended line and the imaginary plane; a sixth step of
executing the second through fifth steps on the plurality of pixels
which can be viewed from the viewpoint position to thereby
determine display colors of the plurality of pixels; a seventh step
of executing the second through sixth steps on all of the plurality
of two-dimensional images; and an eighth step of controlling the
three-dimensional display apparatus to change the color of the
light emitted from the pixel according to the angle at which the
pixel is viewed on the horizontal plane, so that when the display
surface is viewed from the viewpoint positions respectively
corresponding to the two-dimensional images, the pixels may
respectively have the display colors determined in the first
through seventh steps.
2. The stereoscopic image display method according to claim 1,
wherein the three-dimensional display apparatus comprises: a
light-emitting element array structure including a plurality of
one-dimensional light-emitting element arrays arranged at
predetermined intervals in a circumferential direction of the
three-dimensional display apparatus, one-dimensional light-emitting
element arrays each including a plurality of light-emitting
elements longitudinally arranged to form an array; and a
light-shielding portion structure arranged outside the
light-emitting element array structure, the light shielding portion
structure including a plurality of light-shielding portions
arranged at predetermined intervals in the circumferential
direction so as to make the light-shield portion structure have a
plurality of slits arranged at predetermined intervals in the
circumferential direction; and wherein the light-emitting element
array structure and the light-shielding portion structure are
rotated in mutually opposite directions, and light emission of the
light-emitting elements included in the one-dimensional
light-emitting element arrays is controlled, to thereby form the
display surface formed of the pixels in a space between the
light-emitting element array structure and the light-shielding
portion structure.
3. The stereoscopic image display method according to claim 1,
wherein the first step and the second through seventh steps are
executed in real-time.
4. The stereoscopic image display method according to claim 1,
wherein when an image formation surface of the two-dimensional
image is not a simple plane, the imaginary plane is defined as
having the same shape as the image formation surface.
5. The stereoscopic image display method according to claim 1,
wherein in the fifth step, a weighted average operation is
performed to determine the display color of the one pixel according
to a distance between the point of intersection and each of
neighboring points around the point of intersection, based on the
color of the point, corresponding to the point of intersection for
the imaginary extended line and the imaginary plane, on the
two-dimensional image assumed to have been pasted on the imaginary
plane, and colors of points, corresponding to the neighboring
points, on the two-dimensional image assumed to have been pasted on
the imaginary plane.
6. The stereoscopic image display method according to claim 5,
wherein the three-dimensional display apparatus comprises: a
light-emitting element array structure including a plurality of
one-dimensional light-emitting element arrays arranged at
predetermined intervals in a circumferential direction of the
three-dimensional display apparatus, one-dimensional light-emitting
element arrays each including a plurality of light-emitting
elements longitudinally arranged to form an array; and a
light-shielding portion structure arranged outside the
light-emitting element array structure, the light shielding portion
structure including a plurality of light-shielding portions
arranged at predetermined intervals in the circumferential
direction so as to make the light-shield portion structure have a
plurality of slits arranged at predetermined intervals in the
circumferential direction; and wherein the light-emitting element
array structure and the light-shielding portion structure are
rotated in mutually opposite directions, and light emission of the
light-emitting elements included in the one-dimensional
light-emitting element arrays are controlled, to thereby form the
display surface formed of the pixels in a space between the
light-emitting element array structure and the light-shielding
portion structure.
7. The stereoscopic image display method according to claim 5,
wherein the first step and the second through seventh steps are
executed in real-time.
8. A stereoscopic image display method that uses a
three-dimensional display apparatus to present a stereoscopic
image, which can be visually recognized by naked eyes, to a person
located outside the three-dimensional display apparatus, the
three-dimensional display apparatus comprising: a light-emitting
element array structure including a plurality of one-dimensional
light-emitting element arrays arranged at predetermined intervals
in a circumferential direction of the three-dimensional display
apparatus, one-dimensional light-emitting element arrays each
including a plurality of light-emitting elements longitudinally
arranged to form an array; and a light-shielding portion structure
arranged outside the light-emitting element array structure, the
light shielding portion structure including a plurality of
light-shielding portions arranged at predetermined intervals in the
circumferential direction so as to make the light-shield portion
structure have a plurality of slits arranged at predetermined
intervals in the circumferential direction, the three-dimensional
display apparatus having a cylindrical display surface formed of a
plurality of pixels, the display surface being defined by rotating
the light-emitting element array structure and the light-shielding
portion structure at a constant rotational speed ratio, and
controlling light emission of the light-emitting elements included
in the one-dimensional light-emitting element arrays, the method
comprising: a first step of defining a center point of an object to
be displayed as the stereoscopic image, and photographing the
object by a photographic device in all directions from an outside
of the object, centering on the center point of the object to
thereby obtain a plurality of two-dimensional images, or creating
by computer graphics technology a plurality of two-dimensional
pseudo images comparable to the two-dimensional images to be
obtained by photographing the object from the all directions from
the outside of the object, centering on the center point of the
object, and using the two-dimensional pseudo images as the
two-dimensional images; a second step of selecting from among the
two-dimensional images one two-dimensional image and selecting from
among the pixels one pixel which can be viewed from a viewpoint
position corresponding to the one two-dimensional image which has
been selected; a third step of assuming a imaginary plane onto
which the one two-dimensional image selected is pasted, and
arranging the imaginary plane so that an image center point of the
one two-dimensional image corresponding to the center point of the
object may coincide with the center of a cylindrical space for the
cylindrical display surface and that an angle formed between the
imaginary plane and a straight line connecting the viewpoint
position and the center of the cylindrical space for the
cylindrical display surface matches an angle formed between an
image pickup surface of the photographic device and a straight line
connecting the center point of the object and a lens's principal
point of the photographic device; a fourth step of assuming a
imaginary extended line which extends from the viewpoint position
to the imaginary plane through the one pixel selected; a fifth step
of determining a display color of the one pixel as viewed from the
viewpoint position, based on a color of a point on the
two-dimensional image assumed to have been pasted on the imaginary
plane, the point corresponding to a point of intersection of the
imaginary extended line and the imaginary plane; a sixth step of
executing the second through fifth steps on the plurality of pixels
which can be viewed from the viewpoint position to thereby
determine display colors of the plurality of pixels; a seventh step
of executing the second through sixth steps on all of the plurality
of two-dimensional images; and an eighth step of controlling the
three-dimensional display apparatus to change the color of the
light emitted from the pixel according to the angle at which the
pixel is viewed on the horizontal plane, so that when the display
surface is viewed from the viewpoint positions respectively
corresponding to the two-dimensional images, the pixels may
respectively have the display colors determined in the first
through seventh steps.
9. A stereoscopic image display method that uses a
three-dimensional display apparatus to present a stereoscopic
image, which can be visually recognized by naked eyes, to a person
located outside the three-dimensional display apparatus, the
three-dimensional display apparatus comprising: a light-emitting
element array structure including a plurality of light-emitting
elements two-dimensionally arranged on a cylindrical surface; and a
light-shielding portion structure arranged outside the
light-emitting element array structure, the light shielding portion
structure including a plurality of light-shielding portions
arranged at predetermined intervals in a circumferential direction
so as to make the light-shield portion structure have a plurality
of slits arranged at predetermined intervals in the circumferential
direction, the three-dimensional display apparatus having a
cylindrical display surface formed of a plurality of pixels, the
display surface being defined by rotating the light-emitting
element array structure and controlling light emission of the
light-emitting elements included in the light-emitting element
array structure, the method comprising: a first step of defining a
center point of an object to be displayed as the stereoscopic
image, and photographing the object by a photographic device in all
directions from an outside of the object, centering on the center
point of the object to thereby obtain a plurality of
two-dimensional images, or creating by computer graphics technology
a plurality of two-dimensional pseudo images comparable to the
two-dimensional images to be obtained by photographing the object
from the all directions from the outside of the object, centering
on the center point of the object, and using the two-dimensional
pseudo images as the two-dimensional images; a second step of
selecting from among the two-dimensional images one two-dimensional
image and selecting from among the pixels one pixel which can be
viewed from a viewpoint position corresponding to the one
two-dimensional image which has been selected; a third step of
assuming a imaginary plane onto which the one two-dimensional image
selected is pasted, and arranging the imaginary plane so that an
image center point of the one two-dimensional image corresponding
to the center point of the object may coincide with the center of a
cylindrical space for the cylindrical display surface and that an
angle formed between the imaginary plane and a straight line
connecting the viewpoint position and the center of the cylindrical
space for the cylindrical display surface matches an angle formed
between an image pickup surface of the photographic device and a
straight line connecting the center point of the object and a
lens's principal point of the photographic device; a fourth step of
assuming a imaginary extended line which extends from the viewpoint
position to the imaginary plane through the one pixel selected; a
fifth step of determining a display color of the one pixel as
viewed from the viewpoint position, based on a color of a point on
the two-dimensional image assumed to have been pasted on the
imaginary plane, the point corresponding to a point of intersection
of the imaginary extended line and the imaginary plane; a sixth
step of executing the second through fifth steps on the plurality
of pixels which can be viewed from the viewpoint position to
thereby determine display colors of the plurality of pixels; a
seventh step of executing the second through sixth steps on all of
the plurality of two-dimensional images; and an eighth step of
controlling the three-dimensional display apparatus to change the
color of the light emitted from the pixel according to the angle at
which the pixel is viewed on the horizontal plane, so that when the
display surface is viewed from the viewpoint positions respectively
corresponding to the two-dimensional images, the pixels may
respectively have the display colors determined in the first
through seventh steps.
Description
TECHNICAL FIELD
[0001] The present invention relates to a stereoscopic image
display method that eliminates the need for wearing stereoscopic
viewing glasses.
BACKGROUND ART
[0002] The inventors have proposed a three-dimensional display
apparatus which allows many people can simultaneously observe an
image by naked eyes in all directions, namely, 360 degrees around
the image like a multiplex hologram (refer to Non-Patent Documents
1, 2, and 3). The apparatus is configured in such a manner that
one-dimensional light source arrays are composed of one-dimensional
light-emitting elements such as LEDs capable of high-speed
modulation and vertically arranged in a line, and the light source
arrays are rotated inside a cylindrical parallax barrier. This
apparatus is characterized by its capability of displaying an image
at narrower parallax intervals than ever by rotating the
cylindrical parallax barrier in a direction opposite to that of the
light source array. As a three-dimensional display apparatus used
in carrying out the present invention, it is confirmed that a
stereoscopic image can be actually displayed and observed in all
directions by this proposed apparatus (refer to Non-patent Document
4).
[0003] Japanese Patent Publication No. 2003-195214 (Patent Document
1) has proposed a stereoscopic display system that uses a parallax
barrier and a light-emitting array for rotational scanning.
[0004] Japanese Patent Publication No. 10-97013 (Patent Document 2)
has disclosed another example of a stereoscopic image display
system. This stereoscopic image display system uses a
three-dimensional display apparatus to present a stereoscopic
image, which can be visually recognized by naked eyes, to people
located outside the three-dimensional image display apparatus
having a cylindrical image display surface or plane defined
therein. The image display surface is formed of a plurality of
pixels which are respectively configured to emit light of different
colors and brightness as defined according to an angle at which the
pixel is viewed on a horizontal plane.
Non-Patent Document 1: Tomohiro Endo and Makoto Sato, "Cylindrical
Real-Time 3-D Display with Scanned 1-D Light Source Arrays",
Journal of the Institute of Image Information and Television
Engineers of Japan, Vol. 53, No. 3, pp. 399-404, (1999)
Non-Patent Document 2: Tomohiro Endo, Yoshihiro Kajiki, Toshio
Honda, and Makoto Sato, "A Cylindrical 3-D Display Observable from
All Directions", 3-D Image Conference '99 Papers, pp. 99-104
(1999)
[0005] Non-Patent Document 3: Tomohiro Endo, Yoshihiro Kajiki,
Toshio Honda, and Makoto Sato, "Cylindrical 3-D Display Observable
from All Directions", Transactions of The Institute of Electronics,
Information and Communication Engineers D-II, Vol. J84-D-II, No. 6,
pp 1003-1011, (2001)
Non-Patent Document 4: Tomohiro Endo, Toshio Honda, "Cylindrical
3-D Video Display--Color Video Display System--", 3-D Image
Conference 2002 Papers, pp. 89-92 (2002)
Patent Document 1: Japanese Patent Publication No. 2003-195214
(Applicant: Seiko Epson Corporation)
Patent Document 2: Japanese Patent Publication No. 10-97013
(Applicant: Futaba Corporation)
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0006] In the three-dimensional display apparatus described before,
the color and brightness of the light emitted by each of the pixels
is independently controlled according to an angle in the horizontal
direction, or an angle at which the pixel is viewed on a horizontal
plane. Display of a stereoscopic image is thereby performed.
Accordingly, data to be supplied to the three-dimensional display
apparatus is three-dimensional data that specifies the color and
brightness of the light, for three parameters, namely, two
parameters that identify the position of each pixel and an
additional parameter for the angle in the horizontal direction.
Generation of the data of a type as described above for displaying
a target image will be herein referred to as rendering.
[0007] Conventionally, only CG (computer graphics) images are used
in stereoscopic display. In other words, the stereoscopic display
is performed by so-called model-based rendering which is directly
based on a stereoscopic model stored in a computer. In the
conventional method of the stereoscopic display, light beams
emitted from respective pixels 102, 103 on a screen 101 are traced
back from stereoscopic image objects 104 to 106 to be displayed,
thereby determining respective colors of the light beams. The
three-dimensional data described before is thereby generated. This
method is considered to be most readily understood in view of an
idea of reproducing a light beam from the object. In the
conventional method, however, only the data generated offline from
the stereoscopic model within the computer are displayed, and
actually photographed images of a person or the like cannot be
displayed.
[0008] An object of the present invention is to provide a
stereoscopic image display method capable of stereoscopic display
of an actually photographed image and a pseudo photographed
image.
[0009] Another object of the present invention is to provide a
stereoscopic image display method capable of supporting real time
display of an actually photographed image and a pseudo photographed
image.
Means for Solving the Problems
[0010] When an actually photographed image is handled, information
on the image is derived from a plurality of two-dimensional images
having parallaxes (which are also referred to as parallax images).
When these images are displayed as stereoscopic images, it is
necessary to make it possible to selectively view one of the
two-dimensional images according to the position of a viewpoint.
This is the same as an idea of multi-view autosteroscopic
displaying using a lenticular sheet or the like.
[0011] In a stereoscopic image display method of the present
invention, a three-dimensional display apparatus is used to present
a stereoscopic image, which can be visually recognized by naked
eyes, to a person located outside the three-dimensional display
apparatus having a cylindrical display surface defined therein,
wherein the display surface is formed of a plurality of pixels
respectively configured to emit light of different color and
brightness as defined according to an angle at which the pixel is
viewed on a horizontal plane. As the three-dimensional display
apparatus as described above, a three-dimensional display apparatus
developed by inventors of the present invention, for example, may
be employed. The three-dimensional display apparatus developed by
the inventors comprises a light-emitting element array structure
including a plurality of one-dimensional light-emitting element
arrays arranged at predetermined intervals in a circumferential
direction of the three-dimensional display apparatus, each of the
one-dimensional light-emitting element arrays including a plurality
of light-emitting elements longitudinally arranged to form an
array; and a light-shielding portion structure arranged outside the
light-emitting element array structure, the light shielding portion
structure including light-shielding portions arranged at
predetermined intervals in the circumferential direction so as to
make the light-shielding portion structure have a plurality of
slits arranged at predetermined intervals in the circumferential
direction. Then, the light-emitting element array structure and the
light-shielding portion structure are rotated in mutually opposite
directions and timing for light emission of the light-emitting
elements included in the one-dimensional light-emitting element
arrays is controlled under a condition that a rotational speed of
the light-emitting array structure is lower than a rotational speed
of the light-shielding portion structure. Thus, the pixels are
formed in a space between the light-emitting element array
structure and the light-shielding portion structure. Then, the
stereoscopic image that can be visually recognized by naked eyes is
formed by means of light emitted from the pixels, and is presented
to the people outside the display apparatus. In theory, the
light-emitting element array structure and the light-shielding
portion structure may be rotated in the same direction. When
rotating the light-emitting element array structure and the
light-shielding portion structure, both of the structures should be
rotated with a constant speed ratio. When using a light-emitting
element array structure including a plurality of light-emitting
elements two-dimensionally arranged on a cylindrical surface in
place of the light-emitting element array structure formed of the
one-dimensional light-emitting arrays, the light-emitting element
array structure may be fixed, and only the light-shielding portion
structure may be rotated.
[0012] Of course, the method of the present invention may also be
applied when other known three-dimensional display apparatuses as
disclosed in Japanese Patent Publication No. 10-097013 as well as
the three-dimensional display apparatus described above are
employed.
[0013] In the method of the present invention, a center point of an
object to be displayed as the stereoscopic image is defined, and
the object is photographed by a photographic device, centering on
the center point of the object, in all directions from an outside
of the object, thereby obtaining a plurality of two-dimensional
images. Alternatively, a plurality of two-dimensional pseudo
images, comparable to the two-dimensional images capable of being
obtained by photographing the object by the photographic device,
centering on the center point of the object, in the all directions
from the outside of the object, are created by computer graphics
technology, and obtained as the two-dimensional images (a first
step). If data processing is performed later, the obtained
two-dimensional images are stored in a memory. If the data
processing is performed in real-time, the two-dimensional images do
not need to be stored in the memory. The center point of the object
herein refers to a starting point located on the object side for
distance measurement on the object when the object is photographed
by the photographic device in all directions from the outside of
the object with an equal distance maintained between the
photographic device and the object, for example.
[0014] Next, one two-dimensional image is selected from among the
two-dimensional images, and from among the pixels, one pixel which
can be viewed from a viewpoint position corresponding to the
selected one two-dimensional image is selected (a second step). The
viewpoint position herein refers to a position corresponding to the
principal point of lens of the photographic device (camera) that
photographed the selected one two-dimensional image when the center
point of the object is made to coincide with the cylinder center of
the display surface.
[0015] Then, an imaginary plane onto which the one two-dimensional
image selected is pasted is assumed, and is arranged so that an
image center point of the two-dimensional image corresponding to
the center point of the object may coincide with the cylinder
center of the display surface or the center of a cylindrical space
for the cylindrical display surface, and that an angle formed
between the virtual surface and a straight line connecting the
viewpoint position and the cylinder center of the display surface
matches an angle formed between an image pickup surface of the
photographic device (camera) and a straight line connecting the
center point of the object and the principal point of lens of the
photographic device (camera) (a third step). The image center point
herein refers to the point at which the center point of the object
is located or appears on the two-dimensional image.
[0016] Next, an imaginary extended line extending from the
viewpoint position to the imaginary plane through the selected one
pixel is assumed (a fourth step). A display color of the one pixel
as viewed from the viewpoint position is determined based on a
color of a point on the two-dimensional image assumed to have been
pasted on the imaginary plane, the point corresponding to a point
of intersection of the imaginary extended line and the imaginary
plane (a fifth step). Most simply, the color of the point, which
corresponds to the point of intersection, on the two-dimensional
image assumed to have been pasted on the imaginary plane should be
determined as the display color of the pixel which is viewed from
the viewpoint position. However, in order to inhibit aliasing that
may occur when a spatial frequency component higher than the
largest spatial frequency that can be displayed by the display
apparatus is included in the two-dimensional image assumed to have
been pasted on the imaginary plane, it is preferable to perform a
weighted average operation to determine the display color of the
one pixel according to a distance between the point of intersection
and each of neighboring points around the point of intersection,
based on the color of the point, corresponding to the point of
intersection for the imaginary extended line and the imaginary
plane, on the two-dimensional image assumed to have been pasted on
the imaginary plane, and colors of points, corresponding to the
neighboring points, on the two-dimensional image assumed to have
been pasted on the imaginary plane. The largest spatial frequency
that can be displayed by the display apparatus is determined
according to an interval between adjacent pixels and a
discretization interval for the angle in the horizontal direction
by which each pixel can control the color and brightness thereof
independently.
[0017] The second through fifth steps are executed on a plurality
of the pixels that can be viewed from the one viewpoint position,
thereby determining display colors of the plurality of the pixels
(a sixth step). Then, the second through sixth steps are executed
on all of the two-dimensional images with respect to all of the
viewpoint positions corresponding to these two-dimensional images
(a seventh step).
[0018] Then, the three-dimensional display apparatus is controlled
to change the color of the light emitted from the pixel according
to the angle of the emitted light in the horizontal direction, or
the angle at which the pixel is viewed on the horizontal plane, so
that when the display surface is viewed from the viewpoint
positions respectively corresponding to the two-dimensional images,
the pixels may respectively have the display colors determined in
the first through seventh steps, respectively (an eighth step).
[0019] According to the method of the present invention, using the
three-dimensional display apparatus with the pixels arranged
two-dimensionally on the virtual cylindrical display surface, the
two-dimensional image corresponding to each viewpoint position may
be independently displayed. Thus, stereoscopic display of an
actually photographed image or a pseudo image of the actually
photographed image may be performed in real-time.
[0020] When the first step and the second through seventh steps are
executed in real-time, an actually photographed image may be
displayed in real-time.
[0021] The light-emitting elements included in the light-emitting
element arrays typically include light-emitting diodes, laser
diodes, organic ELs, plasma display elements, FEDs, SEDs, and CRTs,
and also include a combination of a spatial light modulator such as
a liquid crystal display device and DMD device, and an appropriate
light source.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is an illustration used for explaining a conventional
method.
[0023] FIG. 2 is an illustration showing a basic structure of a
three-dimensional display apparatus used in an embodiment of the
present invention.
[0024] FIG. 3 is an illustration used for explaining the principle
of a method of the present invention;
[0025] FIG. 4 is an illustration showing how to identify a pixel
when explaining the principle of the method of the present
invention with reference to FIG. 3.
[0026] FIG. 5 is an illustration supplementarily used when
explaining the principle of the method of the present invention
with reference to FIG. 3.
[0027] FIG. 6 is a flowchart showing an example of a software
algorithm used to implement using a computer the second through
eighth steps of the method according to the embodiment of the
present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0028] An embodiment of a stereoscopic image display method
according to the present invention will be described below in
detail with reference to the accompanying drawings.
[0029] FIG. 2 shows a basic structure of a three-dimensional
display apparatus 1 used in this embodiment of the present
invention. This three-dimensional display apparatus 1 comprises a
composite rotational structure 3. The composite rotational
structure 3 comprises a light-emitting element array structure 5
and a light-shielding portion structure 7. The light-emitting array
structure 5 includes a plurality of one-dimensional light-emitting
element arrays 9 that are arranged in a circumferential direction
of the light-emitting array structure at predetermined intervals.
Each one-dimensional light-emitting element array 9 includes a
plurality of light-emitting diode LEDs that are attached to a
supporting member and are longitudinally (or vertically) arranged
to form arrays on the supporting member. In this embodiment, each
of the one-dimensional light-emitting arrays 9 that constitute the
light-emitting element array structure 5 has monochrome
light-emitting diodes that arranged in the vertical direction.
Three types of the one-dimensional light-emitting element arrays,
namely, of red, green, and blue colors are arranged recurrently in
the circumferential direction, thereby constituting the
light-emitting element array structure 5. The one-dimensional
light-emitting element array may also be constituted from a
plurality of light-emitting elements that are longitudinally
arranged, and each of which includes light emitters of the three
colors, red, green, and blue in one package. The one-dimensional
light-emitting element arrays 9 are coupled by thin, ring-shaped
coupling frames (not shown) arranged respectively at upper and
lower positions of the one-dimensional light-emitting element
arrays 9.
[0030] The light-shielding portion structure 7 referred to as a
parallax barrier is arranged outside the light-emitting element
array structure 5, and includes a plurality of light-shielding
portions 8 arranged in the circumferential direction at
predetermined intervals to form a plurality of slits 10 that allow
people located outside the image display apparatus 1 to view a
stereoscopic image. The light-emitting element array structure 5
and the light-shielding portion structure 7 are rotated with a
constant speed ratio. Provided that the light-emitting element
array structure 5 and the light-shielding portion structure 7 are
rotated with the constant speed ratio, rotational directions of the
light-emitting element array structure 5 and the light-shielding
portion structure 7 may be opposite to each other, as shown in FIG.
2, or the rotational directions may be the same. A description of a
driving structure for rotating the light-emitting element array
structure 5 and the light-shielding portion structure 7 is
omitted.
[0031] Some of inventors have already disclosed a basic principle
of the three-dimensional display apparatus 1 used in this
embodiment as described in "Cylindrical 3-D Display using rotating
one-dimensional light source arrays and a cylindrical parallax
barrier" (by Tomohiro Endo, Yoshihiro Kajiki, Toshio Honda, Makoto
Sato, "All-Around Type Three-Dimensional Display", Transactions of
The Institute of Electronics, Information and Communication
Engineers Vol. J84-D-II, No. 6, pp 1003-1011, 2001). A disclosed
prototype apparatus can display different images at a narrow
interval of one degree. An operational principle of the prototype
apparatus is as follows. Both of the light-shielding portion
structure (parallax barrier) 7 and the light-emitting element
structure 5 located inside the light-shielding portion structure 7
are rotated together. The rotational directions are opposite. By
rotation of the one-dimensional light-emitting elements 9 disposed
in the light-emitting element array structure 5, an image may be
displayed on a cylindrical display surface. By rotation of both of
the light-emitting element array structure 5 and the
light-shielding portion structure (parallax barrier) 7, a relative
position between the light-emitting element array structure 5 and
the light-shielding portion structure 7 changes at a high speed.
Accordingly, an orientation of thin luminous flux that passes
through a slit 10 of the light-shielding portion structure 7 is
scanned. Then, by changing brightness of each of the light-emitting
diode elements LEDs that constitute the one-dimensional
light-emitting element arrays in synchronization with the scanning,
light beam reproduction is performed by time division. As a result,
an image (stereoscopic image) that is differently viewed depending
upon a viewing direction may be shown.
[0032] The specification of the three-dimensional display apparatus
1 used in this embodiment is as shown in Table 1. TABLE-US-00001
TABLE 1 Pixel Pitch 1 [mm] No. of Pixels 1254 (H) .times. 256 (V)
Viewing Area Angle 360 degrees (60 degrees per pixel) Light Beam
Angular Interval 1 degree Stereoscopic Image Size F200 .times. 256
[mm] No. of Colors 4096 (12 bits) Frame Memory Capacity 6.9 GB
Video Length 5.4 [s] Dimension of Apparatus 800 W .times. 800 D
.times. 1100 H [mm]
[0033] Specifically, the light-shielding portion structure
(parallax barrier) 7 of the prototype apparatus rotates at a high
speed of 1800 rpm, for example. On contrast therewith, the
light-emitting element array structure 5 of the prototype apparatus
rotates at a speed of 100 rpm.
[0034] In the stereoscopic image display method of the present
invention, the three-dimensional display apparatus 1 as described
above is used, thereby performing stereoscopic display in a manner
that will be described below. A rendering method for carrying out
the method of the present invention will be described with
reference to FIGS. 3 through 5. It is assumed herein that the
three-dimensional display apparatus 1 has a two-dimensional
arrangement of pixels on a cylindrical surface (cylindrical display
surface), constituted by one pixel in a circumferential direction
of the apparatus and m pixels in an axis direction of the
apparatus. A pixel is indicated by P(j, k). As shown in FIG. 4, the
first subscript of P indicates a position in the circumferential
direction, and the second subscript of P indicates a position in
the axis direction of a cylinder. Accordingly, all pixels are
represented by P(1, 1) through P(1, m).
[0035] First, a center point of an object to be displayed as a
stereoscopic image is defined, and the object is photographed by a
photographic device (camera), centering on the center point of the
object, in all directions around or from an outside of the object,
thereby obtaining a plurality of two-dimensional images.
Alternatively, a plurality of two-dimensional pseudo images
comparable to the two-dimensional images that can be obtained by
defining the center of the object and photographing the object by
the photographic device, centering on the center of the object, in
the all directions around or from the outside of the object, are
created by computer graphics technology, and these images are used
as the two-dimensional images (a first step). These two-dimensional
images are stored in a memory as image data that can be processed
by a computer. When the two-dimensional images are actually
photographed images, inputs to the three-dimensional display
apparatus 1 are n two-dimensional images photographed by the
camera, or the actually photographed images, which are indicated by
I(1) to I(n). In this case, photographing may be performed using
only one camera, or a plurality of cameras. A type of the camera is
arbitrary. In view of the subsequent data processing, it is
preferable that photographing is performed by a digital camera.
[0036] Next, one two-dimensional image I(i) is selected from among
the stored two-dimensional images [I(1) to I(n)], and one pixel
P(j, k) that can be viewed or seen from a viewpoint position V(i)
corresponding to the image I(i) is selected from pixels P(j, k) (a
second step). The viewpoint position (Vi) herein refers to a
position corresponding to the principal point of lens of the camera
that photographed the two-dimensional image I(i) when the center
point of the object is made to coincide with a cylinder center O.
When a magnification is different between when the two-dimensional
image was actually photographed and when stereoscopic display is
performed, the position V(i) should be changed according to the
magnification.
[0037] Next, an imaginary plane B(i) with the selected
two-dimensional image I(i) pasted thereon is assumed, and the
imaginary plane B(i) is arranged so that an image center point of
the two-dimensional image I(i) corresponding to the center point of
the object coincides with the center of the cylindrical display
surface or the cylinder center O, and that an angle formed between
a straight line connecting the viewpoint position V(i) and the
cylinder center O and the imaginary plane B(i) matches an angle
formed between a straight line connecting the center point of the
object and the principal point of lens of the camera and an image
pickup surface of the camera (a third step).
[0038] Next, an imaginary extended line PL that extends from the
viewpoint position V(i) to the imaginary plane B(i) through the
selected one pixel P(j, k) is assumed (a fourth step). Actually
data are manipulated to make these assumptions, using the computer.
When an image formation surface obtained at the time of
photographing is a curved surface or a polyhedron, which is not a
simple plane, the imaginary plane B(i) may also be formed to be the
curved surface or other shape the like in accordance with the image
formation surface. The imaginary plane B(i) in this case is
arranged in an appropriate position relative to the viewpoint
position V(i) in accordance with a photographing situation.
[0039] Next, a display color C(i, j, k) of one pixel P(j, k) as
viewed in a direction D(i, j, k) from the viewpoint position V(i)
is determined, based on a color of a point on the two-dimensional
image assumed to have been pasted on the imaginary plane B(i), the
point corresponding to a point of intersection of the imaginary
extended line PL and the imaginary plane B(i) (a fifth step). In
theory, the color of a point, which corresponds to the point of
intersection, on the two-dimensional image assumed to have been
pasted on the imaginary plane B(i), should be determined as the
display color C(i, j, k) for the one pixel P(j, k) as viewed in the
direction D(i, j, k) from the viewpoint position V(i). However,
when a spatial frequency component higher than the largest spatial
frequency that can be displayed by the display apparatus is
included, aliasing may occur in the two-dimensional image I(i)
assumed to have been pasted on the imaginary plane. Then, in order
to control aliasing, it is preferable to perform a weighted average
operation to determine the display color C(i, j, k) of one pixel
according to a distance between the point of intersection and each
of neighboring points around the point of intersection, based on
the color of the point, corresponding to the point of intersection
for the imaginary extended line and the imaginary plane, on the
two-dimensional image assumed to have been pasted on the imaginary
plane, and colors of points, corresponding to the neighboring
points, on the two-dimensional image assumed to have been pasted on
the imaginary plane. When the weighted average operation as
described above is performed, the maximum value of the spatial
frequency of the two-dimensional image I(i) may be substantially
limited. Occurrence of aliasing can be thereby controlled.
[0040] The largest spatial frequency that can be displayed by the
display apparatus is determined based on a pixel interval and a
discretization interval of an angle in the horizontal direction by
which each pixel can control the color and brightness of the pixel
independently.
[0041] The second through fifth steps are executed on a plurality
of pixels P that can be viewed or seen from the one viewpoint
position V(i), thereby determining display colors of the pixels P
(a sixth step). Then, the second through sixth steps are executed
on all of the two-dimensional images with respect to all of the
viewpoint positions V(i) corresponding to these two-dimensional
images (a seventh step). Then, timing for light emission for the
light-emitting elements LEDs included in the one-dimensional
light-emitting element arrays 9 is controlled so that when the
display surface is viewed from the viewpoint positions, all the
pixels have the display colors determined in the first through
seventh steps (an eighth step). In other words, the
three-dimensional display apparatus is controlled to change the
color of light emitted from each of the light-emitting elements
LEDs according to the angle of the emitted light in the horizontal
direction or the angle at which the pixel is viewed from the
viewpoint position on the horizontal plane, so that when the
display surface is viewed from the viewpoint positions respectively
corresponding to the two-dimensional images, the pixels may
respectively have the display colors determined in the first
through seventh steps. The light-emitting elements LEDs are driven
by a light-emitting element driving device not shown. FIG. 6 is a
flowchart showing an example of a software algorithm used to
implement using a computer the second through eighth steps
described above.
INDUSTRIAL APPLICABILITY
[0042] According to the method of the present invention, it is
possible to implement stereoscopic image display of an actually
photographed image or pseudo photographed image using a
three-dimensional display apparatus, wherein people outside the
display apparatus may visually recognize the stereoscopic image by
naked eyes as viewed in all directions. The display apparatus has a
cylindrical display surface defined therein, which are formed of a
plurality of pixels respectively configured to emit light of
different color and brightness as defined an angle of the emitted
light in the horizontal direction or an angle at which the pixel is
viewed from the viewpoint position on a horizontal plane.
* * * * *